It has become common practice to use center pivot irrigation systems in the irrigation of large fields and these typically comprise a long water conduit which is pivotally connected at one end to a source of water under pressure. The conduit arm is carried in an elevated position by a plurality of spaced wheels mounted on wheel towers which are powered by hydraulic, pneumatic, or electric motors to rotatably sweep the central conduit over a circular pattern in a field. The center conduit includes a plurality of water sprinkling heads spaced over its length for distributing a spray of water on the circular field area as the center pivot irrigation conduit passes thereby. Center pivot irrigation systems have been successful for uniform distribution of water over a field crop and initially were operated at reasonably high water pressures. Current systems typically work with a somewhat lower water pressure and require that sprinkler heads distribute water evenly as the center pivot irrigation conduit moves through a field. A typical patent for a center pivot irrigation system can be seen in the Vikre patent, U.S. Pat. No. 4,356,972, which mounts the sprinkler heads on top of the central irrigation center pivot conduit. The sprinkler head uses a deflector head for deflecting the water with a grooved deflector pad. Other self-propelled mechanically moving irrigation machines can irrigate in a different manner, such as moving laterally in a straight line through a field.
There have been a number of wobbling sprinkler heads used in the past in which the water distribution head of the sprinkler, instead of being rotated in a smooth rotation or instead of following one of the other sprinkler patterns, has a water distribution head which wobbles in a rotating fashion to provide a more even distribution of water. In the Clearman patents, U.S. Pat. No. 4,487,368 and U.S. Pat. No. 4,773,594, a control pattern wobbling sprinkler is provided in which a rotating sprinkler head has a wobbling water distribution head mounted on the end thereof which has a plurality of vanes formed in the wobbling portion of the head to force a wobbling motion which results from the loose connection between the distribution head and the supporting arm of the sprinkler head. In the sprinkler of these two patents, a base is provided for ground support and a rotating sprinkler head has the end of the rotating arm bent at an angle so that the loosely attached wobbling head tilts groundward when not being used. Upon initiation of water under pressure to the head, the head is already in a cocked position and forces a rotating action which causes a wobbling rotation of the water head portion. In the J. M. Hait patent, U.S. Pat. No. 3,009,648, an irrigation system is provided in which the sprinkler head has a rotating stream of water issuing therefrom but allows a deflection head to move back and forth. In J. O. Hruby, Jr., U.S. Pat. No. 3,034,728, a lawn sprinkler is shown which has a centrally disposed and vertically extending stem which is made to rotate by the action of the water passing through the sprinkler. The stem is loosely mounted and has an uneven deflecting portion to produce a rotating action of the spray. In the M. S. Aubert patent, U.S. Pat. No. 3,091,400, a dishwashing machine has a rotary wobbling spring head which is driven by the water momentum to wobble the head in a dishwasher.
In Applicant's U.S. Pat. No. 5,381,960, a wobbling irrigation sprinkler head includes a magnet for the initial tilt in a wobbling irrigation sprinkler head for use on a self-propelled mechanical moving irrigation system, such as a center pivot field irrigation system, having the wobbling sprinkler head facing downward from the water supply conduit. This sprinkler head produces a wobbling motion as a result of the nozzle directing water onto a deflector pad having a predetermined shape with water deflecting grooves which rotates and wobbles the water deflecting head. A magnet is mounted in the sprinkler head base to attract a ferric metal washer mounted in the wobbling deflecting head to tilt the wobbling water deflector head relative to the base to cock the deflector head to initiate the wobbling in the deflector head.
In Applicant's prior U.S. patent application Ser. No. 08/954,238 for a Wobbling Sprinkler Head, a wobbling irrigation sprinkler head is for use on a self-propelled mechanical moving irrigation system, such as a center pivot field irrigation system, in which the sprinkler heads face downward from the water supply conduit. This sprinkler head produces a wobbling motion as a result of the nozzle directing water onto a deflector pad having a predetermined shape with water deflecting grooves which cause a rotation and wobbling of the water deflecting head. The wobbling motion is produced by a wobble mechanism which has a pair of interacting wobble generating members, one mounted on the water deflection head and the other mounted on the sprinkler body to keep the water deflection head tilted at an angle to the water exiting the water nozzle. The interaction of the protruding members forces the deflection head to start wobbling as the deflection head rotates and maintains the wobble. The water deflection head is blocked from the center axis position to keep the water deflecting surface at an angle to the stream of water being emitted from the nozzle.
One of the problems that occurs with a commercial wobble sprinkler head is the vibration created in the sprinkler head by the wobbling action which can result in wear and premature failure of the sprinkler head. The present invention is a wobbling sprinkler head which reduces the vibration in the sprinkler head. A water deflection head is rotated by a stream of water from a water nozzle. The interaction of a pair of wobble generating members forces the water deflection head to start wobbling as the deflection head rotates. The water deflection head is prevented from the center position by the interacting wobble generating members to keep the water deflecting surface at an angle to the stream of water being emitted from the nozzle. Once the deflection head starts rotating, the protruding members do not touch since the circle of rotation is outside a stationary wobble generating member. A predetermined mass is removably attached to the sprinkler head along the base of the sprinkler head to dampen vibrations in the sprinkler head generated by the wobbling deflector head. The mass is removably attached to allow for the change of the mass depending upon the operating conditions of the sprinkler head.